1. Field of the Invention
This invention relates to a fixed-high-power-switching microscope especially for use in medical practice, which can be switched from a usual variable magnification to a fixed high magnification during viewing, as necessary.
2. Description of the Related Art
In the medical field, microscopes for use in surgical operations are stereoscopic microscopes (stereomicroscopes) which provide stereoscopic views of affected areas. More specifically, a stereomicroscope guides two-channel beams of light reflected off an affected area via an objective optical system, a variable power optical system and an eyepiece optical system to the two eyes of a doctor. The doctor, with the eyes fixed to the eyepiece optical system for viewing, magnifies the affected area within the view by means of the variable power optical system (zooming), as necessary, conducting necessary procedure to the affected area with the hands extended.
However, such a conventional microscope having a variable power optical system has a magnification limit in providing a clear high-resolution view of an affected area. More specifically, a variable power optical system has a limit in magnification (some 25 times) and cannot provide sufficient resolution when the magnification is increased thereover, resulting in a blurred image of an object being viewed. The conventional microscope thus has limited application in surgical operations, and cannot be used for connection of small blood vessels (of a diameter of some hundreds of micro-meters) for cure of a severed finger or for a surgical operation on a cultured tissue produced by biotechnology.
In this context, the provision of a microscope which provides high-resolution views without blurring images at a high magnification exceeding usual magnifications (hereinafter referred to as xe2x80x9clow magnificationsxe2x80x9d) has been expected. It is not practical to manufacture a high-magnification/high-resolution microscope with a variable power optical system excluded, for exclusive use in microsurgery because it becomes necessary to exchange the microscope in its entirety when usual magnifications are required for entire viewing. Thus the provision of a microscope which can be used both in surgical operations at usual magnifications for a wide field of view and in microsurgery at high magnification and high resolution has been expected.
This invention has been made to meet such a demand, and provides a variable magnification microscope equipped with a low-magnification optical system which can be easily switched to a high-resolution optical system.
According to a first technical aspect of this invention, there is provided a variable magnification microscope having an objective optical system, a variable power optical system, an eyepiece optical system where the variable power optical system and the eyepiece optical system being arranged on a first optical axis passing through the objective optical system, a high power optical system arranged on a second optical axis where the second optical axis bypassing the variable power optical system between the objective optical system and the eyepiece optical system, and a reflecting means selectively disposed in the first optical axis between the objective optical system and the variable power optical system where the reflecting means diverting the first optical axis to the second optical axis.
According to a second technical aspect of this invention, the variable magnification microscope further has a first illuminating system for illuminating a field of view of the variable power optical system, and a second illuminating system for illuminating a field of view of the high power optical system, wherein with the variable power optical system selected, illuminating light only from the first illuminating system is emitted, and with the high power optical system selected, illuminating light from the first and the second illuminating systems is emitted.
According to a third technical aspect of this invention, there is provided an illuminating system for a microscope including a first optical system having a light source for producing a parallel light beam, a first reflecting means, a second reflecting means where between the first reflecting means and the second reflecting means the main axis of an optical path of the parallel light beam being parallel with the main axis of the first optical system and the second reflecting means being fixed relative to the first optical system, and a third reflecting means fixed relative to the first optical system where the third reflecting means being off the main axis of the first optical system, the optical path of the parallel light beam passing via the second reflecting means and the third reflecting means and intersecting the main axis of the first optical system at the focal position of the first optical system.